Well, even a broken clock is right twice a day. It might be pure chance. I think what they might be doing is just finding any water in OSM and adding nodes alongside (and sometimes inside) it tagged natural=beach. They might even be intentionally making some good edits to make our work more difficult (it means that we have to review each change to see if it might be valid).
Does anyone know what other features are of interest to Pokemon players? I have noticed some fake parks being added (and dog parks changed to parks).
Thanks Andy! It is appreciated.